FWD vs. RWD patterns

[Dave Williams]

-> different bolt pattern (the Iron Duke was a Pontiac design from the
-> 60's and had a BOP pattern?).

 The Iron Duke was based on the Chevy II four cylinder of the early
'60s, which was a shortened version of the "new" series Chevy inline
six.  It was discontinued by the latter half of the '60s.  Pontiac
Division resurrected the Chevy II motor as the Iron Duke due to problems
with the Vega four, which was originally a Pontiac design.  The Iron
Duke was rumored to have been in the last few Pontiac Astres that were
built, but I've never seen one.   After the Vega was discontinued there
was a need for a four in other carlines and the Iron Duke went there.
It was later updated as the Tech IV with a crossflow head, and again
into the Quad 4.

 Though the original Chevy II motor shared the usual Chevy transmission
bolt pattern, I'm sorry to say I have no idea what patterns were used on
the Iron Duke, Tech IV, and Quad 4's various RWD/FWD incarnations.